Idle system



March 13, 1962 D. M. GORDON IDLE SYSTEM 4 Sheets-Sheet 1 Filed Aug. 4, 1958 March 13, 1962 D. M. GORDON IDLE SYSTEM 4 Sheets-$heet 2 Filed Aug. 4, 1958 INVENTOR DWIGHT M.GORDON ATTORNEY March 13, 1962 Filed Aug. 4, 1958 4 Sheets-Sheet 3 INVENTOR DWIGHT M. GORDON ATTORNEY March 13, 1962 D. M. GORDON IDLE SYSTEM 4 Sheets-Sheet 4 Filed Aug. 4, 1958 INVENTOR BY DWIGHT M. GORDQN ATTORNEY Unite States 3,025,040 IDLE SYSTEM Dwight M. Gordon, Farmington, Mich, assignor to ACE Industries, Incorporated, New York, N.Y., a corporation of New Jersey Filed Aug. 4, 1958, Ser. No. 752,979 7 Ciaims. (Cl. 261-41) The invention relates to carburetors for internal combustion engines, and more particularly to carburetor idle systems.

The invention is particularly concerned with a carburetor having an idle system which includes a by-pass for by-passing air for idling from above the throttle valve in the carburetor to a point below the throttle valve, and means for adjusting the flow of air through the by-pass to determine the correct idle speed of the engine supplied with air/fuel mixture by the carburetor. This by-pass is used in order to minimize the possibility of faulty operation which might otherwise be caused by the accumulation of gummy deposits and dirt in the throttle bore at the point in the bore where the throttle valve seats. In a carburetor without such a by-pass, such accumulation may cause a decrease in idle speed (due to impedance by the accumulation to the leakage of air around the throttle valve when it is in idling position) to the point of frequent stalling of the engine, and may necessitate frequent and costly cleaning of the carburetor.

With the by-pass idle air system, trouble due to accumulation of gummy deposits and dirt is minimized; the throttle valve may seat tightly in the throttle bore; and at most only a very slight loss of speed may result from loss of air leakage around the throttle valve. However, the by-pass idle air system has had the disadvantage that it complicates adjustment of the idle system to obtain the proper idle air requirement for an engine. In this respect, it is to be observed that the idle air requirement of an automotive vehicle engine depends not only on the efiiciency of the engine, but also the load that it must carry while idling. This load may or may not include such factors as load due to such accessories as an air conditioner compressor, or an air compressor for an air suspension system, or the like. Thus, for equivalent engine idling speed, one vehicle may have an entirely different idle air requirement than another, thus making it desirable that a production-line carburetor be readily adjusted to suit different demands. Present by-pass idle air systems present adjustment complications because a change in the setting of the means for adjusting the flow of air through the bypass changes the air/fuel ratio of the mixture supplied by the carburetor, not only at dead idle, but also in the offidle range of throttle valve position. Accordingly, it has been necessary in adjusting previous carburetors with the bypass idle air system to compensate for the change in mixture ratio caused by changing the setting of by-pass air adjusting means by adjusting the usual idle fuel needle in the idle mixture passage. However, while this adjustment compensates for the change in the mixture resulting at idle by the change in the setting of the by-pass air adjusting means, it does not compensate in the off-idle and early part-throttle range, and it has been found that the amount of air delivered through the by-pass has an undesirable leaning effect on the mixture in this range.

Accordingly, it is an object of this invention to provide a by-pass idle air system which enables simplified adjustment to obtain the proper idle air requirement for the engine (thereby to obtain the proper engine idle speed) and the proper idle mixture, without adversely affecting the mixture ratio in the off-idle and early part-throttle range. In general, this is accomplished by providing an air bleed passage interconnecting the idle mixture passage of the carburetor and the air by-pass and in communi- 3,025,940 Patented Mar. 13, 1962 cation with the air by-pass upstream from the adjusting means in the air by-pass with respect to the direction of air flow through the by-pass, the arrangement being such that air is adapted to bleed through the air bleed passage to the idle mixture passage at a decreasing rate as the rate of air flow through the air by-pass is increased. With this arrangement, adjustment is simplified in that once the idle fuel needle has been set to obtain the proper idle mixture for any given idle speed of the engine, the idle speed may be changed over a relatively wide range simply by changing the setting of the adjusting means in the air by-pass, without adversely affecting the mixture ratio supplied in the off-idle and early part-throttle range. Thus, the carburetor is less sensitive to mixture ratio changes due to different idle air requirements and makes idle speed setting easier in the factory or by the dealer or customer. Other objects and features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the constructions hereinafter described, the scope of the invention being indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

FIG. 1 is a plan view of a four-barrel carburetor in which the invention is incorporated;

FIG. 2 is a vertical section taken on line 2-2 of FIG. 1;

FIGS. 3 and 4 are vertical sections taken on lines 3-3 and 4-4, respectively, of FIG. 1;

FIG. 5 is a horizontal half-section taken on line 5-5 of FIG. 3, appearing as if the cover for the carburetor were removed;

FIG. 6 is a vertical section taken on line 66 of FIG. 1;

FIGS. 7 and 8 are enlarged vertical sections taken on lines 7-7 and 88, respectively, of FIG. 1; and

FIG. 9 is a horizontal section taken on line 9-9 of FIG. 4.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring to the drawings, the invention is illustrated in its application to a multi-barrel multi-stage carburetor of the type commonly referred to as a four-barrel carburetor. As shown, the carburetor comprises a main body casting 1 which is formed to provide a throttle body section 3 and a float bowl section 5 on the throttle body section. The throttle body section 3 has lugs 7 for attachment to the intake manifold of the engine on which the carburetor is used. The float bowl section is generally of rectangular shape in plan, its side walls being designated 9 and 11 and its end walls being designated 13 and 15. Partitions 17 and 19 extend between the side walls 9 and 11 adjacent the end walls 13 and 15 to define two float bowls 21 and 23, one at each end of the fuel bowl section 5. Each of the partitions 17 and 19 has a central inwardly directed offset 25 providing a vertically extending recess such as indicated at 27. A partition 29 extends between oifsets 25 dividing the space bounded by side walls 9 and 11 and partitions I7 and 19 into a primary section 31 and a secondary section 33. The primary section is formed to provide two side-byside primary mixture condnits or barrels 35 and 37, and the secondary section is formed to provide two side-by-side secondary mixture conduits or barrels 39 and 41. Each primary barrel is formed as a venturi. Secured to the top of the fuel bowl section is a float bowl cover 43 formed to provide a circular air horn 45. The horn has a diametrical partition 47 coplanar with partitions 29 dividing it into a primary air inlet 31a above section 31 and a secondary air inlet 33a above section 33.

The cover 43 has a fuel inlet 49 and an inlet passage 51 connecting the inlet to the two fioat bowls 21 and 23. Entry of fuel to the bowls from passage 51 is controlled by two float valves 55, one for each bowl (see FIG. 6). Each of these valves is controlled by a float 55 in the respective bowl. The valves and floats may be of any suitable construction, their details not being critical so far as this invention is concerned. The bowl 21 supplies the barrel 35 and the bowl 23 supplies the barrel 37 via identical systems. Only the system for barrel 35 will be described, and it will be understood that the system for barrel 37 is identical.

Barrel 35 has an upwardly facing shoulder 57 at the side thereof toward the respective float bowl 21 (see F1 2). Extending down from this shoulder is a vertical Well 59. The casting 1 is formed with a passage 61 from the bottom of recess 27 of bowl 21 to the bottom of the well 59. This passage is formed by drilling a vertical hole 63 extending down from the bottom of recess 27 to an intersection with an inclined hole 65 drilled from the bottom of throttle body section 3 to the lower end of the well. The outer end of hole 65 is plugged as indicated at 67. Threaded in the upper end of hole 53 is a metering jet as. A metering rod 71 extends down in recess 27 and through the jet from a vacuum-responsive control contained in the float bowl section under a cap 73 The metering rod and control are of known construction and need not be further described, details thereof not being critical so far as this invention is concerned. It Will be understood that the control for the rod acts to move the metering rod up and down in response to change in intake manifold vacuum, for high speed fuel metering.

Shoulder 57 serves to support a nozzle body 75 (see FIGS. 2, 7 and 8) at the upper end of the primary barrel. This body comprises a casting formed to provide a head 77, an arm 79 extending from the head, and a boost venturi 51 at the outer end of the arm. The head is secured on shoulder 57 as by screws 53. A hole 85 is drilled through the head 77 and the arm 53 from the outside of the head to open into the boost venturi 31. The outer end of this hole is closed as by a welch plug 87. The hole 85 is angled downward from the outside of the head to the boost venturi 81. A hole 59 is drilled up from the bottom of the head to an intersection with angled hole 85. A hole 91 of smaller diameter than hole 39 is drilled to extend up from angled hole 55 coaxial with hole 89, and to an intersection with a horizontally extending hole 93 drilled in head 77 adjacent its upper end (see FIG. 8).

A fuel tube 95 has its upper end pressed in hole 89 and extends down into the well 59. An idle fuel tube 97 of smaller diameter than tube 95 has its upper end pressed into hole 91 and extends down within the tube 95. Idle tube 97 has a restricted lower end 99 which extends down below the lower end of tube 95. A nozzle tube 151 is pressed in the angled hole 35, extending from hole 89 through the arm 79 into the venturi 81. The space 103 between tubes 95 and 97 and the nozzle tube 1131 provides a high speed fuel passage from the well 59 to the boost venturi 81.

Idle orifice tube 97 is part of a low speed circuit for delivering fuel at low speed operation to idle port 165 (see FIG. 4) in the primary barrel. The low speed idle circuit includes holes 91 and 93 in the nozzle head 77. Head 77 has a vertical hole 107 (see FIG. 8) extending up from its bottom with a restricted air bleed hole 109 through the upper end of the head. Hole 93 has a restricted economizer passage 111 extending from its inner end into the vertical hole 197. An air metering plug 113 is pressed in the outer end of hole 93. Air from the air horn 45 passes through and is metered by plug 113 into the hole or passage 93. Air bleeds into the vertical hole 107 from the air horn through bleed hole 109 to lean the mixture delivered through the economizer 111. The vertical hole 107 is aligned with a hole 115 (see FIG. 9) extending down from shoulder 57 which constitutes part of a passage 117 for flow of fuel-air mixture from hole 107 to the idle port 105. Passage 117 is formed by a horizontal bore 119 drilled at an angle through side walls 9 to an intersection with hole 115, and a vertical bore 121 drilled down through side wall 9 (FIG. 4) to an intersection with a horizontal passage 123 which is drilled to provide the idle port 105. The upper end of vertical bore 121 above horizontal bore 119 is plugged as indicated at 125. The outer end of idle port hole 123 is plugged as indicated at 12-7. The outer end of horizontal bore 119 is plugged as indicated at 128 in FIG. 9. The vertical hole 121 extends down past idle port hole 123 to an intersection with an idle adjusting screw port hole 129. An idle adjusting screw 131 having a fuel needle end 133 is threaded in hole 129. A coil compression spring 135 surrounds screw 131, reacting from the side wall 9 against the head 137 of the screw 131.

Head 77 has a second vertical hole 139 (see FIG. 7) in the upper end of which is pressed a nozzle bleed tube 141 having a restricted upper end 143. The bottom of the head is formed with a slot 145 connecting the lower end of the vertical hole 139 and the hole 89 for communication between the hole 139 and the well 59. Fuel tube 95 has a hole 147 adjacent its upper end directed toward the slot 145. This allows air to bleed into the space 163 between tubes 95 and 97.

Each of the primary barrels 35 and 37 has the usual primary throttle valve 149 (see FIGS. 2 and 4) at its lower end, the two primary throttle valves being fixed on the usual primary throttle shaft 151 journalled in the throttle body section. Each primary throttle bore is designated 153. Each throttle valve, when at dead idle, is fully seated around its perimeter on the bore, and is grooved on the bottom as indicated at 155 on the side toward the idle port 105 to provide a restricted opening from the idle port into the throttle bore when the throttle valve is fully seated. The main body casting 1 is formed with a by-pass designated in its entirety by the reference character 157 (see FIGS. 1 and 3) for by-passing air for idling from the upper end of the primary section 31 to the primary throttle bores 153 below the primary throttle valves 149. As shown, this idle air by-pass 157 is common to the two primary barrels, being constituted by a vertical hole 159 extending downward in the portion 161 of casting 1 between the primary barrels 35 and 37 to an intersection with a horizontal hole 163 extending inward from side wall 9 of the casting, and a vertical hole 165 extending up from the bottom of the casting 1 to hole 163 and offset outward from the hole 159. An idle air adjusting screw 167 is threaded in the horizontal hole 163. This screw has an unthreaded inner end portion 169 which traverses the upper end of the hole 165, and is adapted to be threaded in or out to vary the size of the opening from hole 163 into hole 165. A coil compression spring 171 surrounds screw 167, reacting from side wall 9 against the head 173 of the screw.

In accordance with this invention, horizontal channels 1.75 (see FIG. 9) are drilled approximately at right angles to the horizontal bores 119 intersecting the latter and extending to the vertical hole 159 which constitutes the upper part of the idle air by-pass 157 upstream from (above) the idle air adjusting screw 157. These channels 175 thus serve to interconnect the two idle mixture passages 117 and the idle air by-pass 157, with the connection to passages 117 at points downstream (below) economizers 111 and air bleeds 109 therefor, and with the connection to by-pass 157 at a point upstream from (above) the idle air adjusting screw 167. Pressed in each of the channels 175, and located between the verti cal bores 121 and hole 159, is a restriction jet 177. The outer end of each channel 175 is plugged as indicated at 179.

In the primary air inlet portion 31a of the air horn 45 is the usual choke valve 131, the usual choke control being indicated at 183 in FIG. 1. The carburetor has the usual accelerator pump such as indicated at 185 in FIG. 6 for supplying fuel to the primary barrels in re sponse to opening of the primary throttles via a pump discharge jet cluster indicated at 187 in FIGS. 1-3. Vents such as indicated at 189 are provided for venting the float bowls to the interior of the air horn 45.

At the upper end of each secondary barrel 39 and 41 is a venturi cluster 1% having a fuel nozzle 195 supplied with fuel from the respective float bowl via a passage part of which is indicated at 197 in FIG. 4-. Each secondary barrel has the usual secondary throttle valve 199 at its lower end, the two secondary throttle valves being fixed on the usual secondary throttle shaft 2121 journalled in the throttle body section 3. Each secondary barrel also has the usual velocity valve 203 therein, the two velocity valves being fixed on shaft 205 which carries weights such as indicated at 2117 (FIGS. 3 and 5) for biasing the velocity valves closed.

At the ends of the carburetor, as shown in FIG. 1, are the usual mechanisms for controlling the primary throttle shaft 151 and the secondary throttle shaft 201. It will be understood that these mechanisms include such components as the usual actuating lever 2G9 fixed on one end of the primary throttle shaft 151 adapted for connection of an actuating rod for actuating the primary throttle shaft from the usual pedal, the usual fast-idle cam 211 connected as indicated at 213 to the choke valve shaft 215, and the usual mechanism such as indicated at 217 for operating the secondary throttle shaft 201 to open the secondary throttle valves 199 on opening of the primary throttle valves a predetermined amount. Details of these mechanisms are not critical insofar as this invention is concerned, and further detailed description thereof is therefore omitted.

Operation is as follows:

It will be understood that at dead idle, the primary throttle valves 149 are fully seated in the primary throttle bores 153. As to each of the primary barrels 35 and 37, fuel for idling is supplied from well 59, metered through the idle orifice tube 97, and thence passes through holes 91 and 93, economizer passage 111, idle mixture passages 1417 and 117 and thence through idle port 195 and port 12?. Air entering hole Q3 through the metering plug 113 initiates atomization of the fuel, and the flow of the air/fuel mixture is accelerated in passing through the economizer 111. Air entering hole 107 through the bleed hole 1&9 leans the mixture and accelerates its delivery to the idle port 105. The channels 175 constitute metering passages interconnecting the upper part (the inlet side) of the idle air by-pass 157 to the two idle mixture passages 117 for the two primary barrels 35 and 3'7, and act to supply air from the by-pass 157 to the idle mixture passages 117. This air constitutes a further part of the air for the idle mixture, additive to the air supplied through metering plug 113 and bleed hole 189. All this air constitutes part of the air required for idling the engine. Additional air for idling passes directly through the idle air by-pass 157. Some further air for idling may be supplied by leakage of air such as may occur past the primary and secondary throttle valves, around the throttle shafts, etc.

The amount of air bled through metering passages 175 into the idle mixture passages 117 is dependent upon the rate of flow of air through the idle air by-pass 157. The rate of flow through the latter is dependent upon the setting of the idle air adjusting screw 167. With increased flow of air through by-pass 157, the pressure at the ends of passages 1'75 toward the by-pass 157 decreases. Thus, with increased flow of air through by-pass 157, bleeding of air through passages 175 into the idle mixture passages 117 decreases, and the mixture supplied through passages 117 richens up to compensate for increased air flow through by-pass 157 (which would otherwise lean the mixture supplied to the engine).

Accordingly, adjustment of the idle air adjusting screw 167 within relatively wide limits has no effect on the idle mixture ratio, since backing off the screw 167 results in reducing the bleeding of air through passages 175 and advancing the screw 167 results in increasing the bleeding of air through passages 175. Consequently, once the idle fuel adjusting needles 133 have been set to obtain the proper idle mixture for any given idle speed of the engine, it is possible to change the speed over a relatively wide range simply by adjusting the idle air adjusting screw 167, without any necessity for resetting the idle fuel adjusting needles. Moreover, adjustment of the idle air adjusting screw 167 even over a relatively wide range (four to five turns of the screw with the construction as herein illustrated) has little effect to change the mixture ratio supplied by the idle system at off idle and early part-throttle. Thus, the passages 175 provide such compensation as to maintain the mixture ratio at the desired value throughout the entire idle delivery (including off idle and early partthrottle), and eliminate the leaning effect on the mixture which would be present in a system without such passages in the off idle and early part-throttle range.

In view of the above, it will be seen that the several objects of the invention are achieved and other advan tageous results attained.

As various changes could be made in the above constructions without departing from the scope of the inven tion, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. A carburetor for an internal combustion engine, said carburetor comprising a body having a source of fuel therein and a fuel and air mixture conduit there through, a throttle valve mounted within said mixture conduit for movement between an open and a closed position, means forming an idle system for supplying a mixture of air and fuel for idling to said mixture conduit, said means including a port through the wall of said mix ture conduit adjacent to said throttle when in closed position and an idle mixture passage extending from said fuel source to said port, a bypass passage in said carburetor body opening at one end to the ambient space on one side of said throttle and at another end to the ambient space on the other side of said throttle for by-passing air around said throttle, an air bleed passage interconnecting said idle mixture passage and said by-pass passage to provide a flow of air from said by-pass passage into said idle system, and means for adjustably controlling the fiow of air through said by-pass passage inversely to the flow of air through said air bleed passage.

2. A carburetor for an internal combustion engine, said carburetor comprising a body having a source of fuel therein and a fuel and air mixture conduit therethrough, a throttle valve pivotally mounted within said mixture conduit for movement between an open and a closed position, means forming an idle system for supplying a mixture of air and fuel for idling to said mixture conduit, said means including a port through the wall of said mixture conduit adjacent to said throttle when in closed position and an idle mixture passage extending from said fuel source to said port, a by-pass passage in. said carburetor body extending from said mixture conduit on one side of said throttle to ambient space on the other side of said throttle for by-passing air around said throttle, means in said by-pass passage for controlling the flow of air therethrough, and an air bleed passage interconnecting said idle mixture passage and said by-pass passage upstream from said air flow controlling means with respect to the flow of air through said by-pass passage.

3. A carburetor for an internal combustion engine, said carburetor comprising a body having a source of fuel therein and a fuel and air mixture: conduit therethrough, a throttle valve pivotally mounted within said mixture conduit for movement between an open and a closed position, means forming an idle system for supplying a mixture of air and fuel for idling to said mixture conduit, said means including a port through the wall of said mixture conduit adjacent to said throttle when in closed position, an idle mixture passage extending from said fuel source to said port and a restricted opening into said idle mixture passage from ambient space upstream of said throttle, a bypass passage in said carburetor body extending at one end thereof from said ambient space upstream of said throttle to another end thereof opening into ambient space downstream of said throttle for by-passing air around said throttle, an adjustable restriction in said by-pass passage for controlling the flow of air therethrough, and an air bleed passage extending from said idle mixture passage downstream of said restricted opening to said by-pass passage upstream of said adjustable restriction.

4. A carburetor for an internal combustion engine, said carburetor comprising a body having a source of fuel therein and a fuel and air mixture conduit therethrough, a throttle valve pivotally mounted within said mixture conduit for movement between an open and a closed position, means forming an idle system for supplying a mixture of air and fuel for idling to said mixture conduit, said means including a port through the wall of said mixture conduit adjacent to said throttle when in closed position, an idle mixture passage extending from said fuel source to said port and a restricted opening into said idle mixture passage between said fuel source and said port from ambient space upstream of said throttle, a by-pass passage in said carburetor body extending at one end thereof from said ambient space upstream of said throttle to another end thereof opening into ambient space downstream of said throttle for bypassing air around said throttle, an adjustable restriction comprising a metering screw in said by-pass passage for controlling the flow of air therethrough, and an air bleed passage extending from said idle mixture passage between said restricted opening and said port to said by-pass passage upstream of said adjustable restriction.

5. A carburetor for an internal combustion engine, said carburetor comprising a body having a source of fuel therein and a pair of fuel and air mixture conduits therethrough, a different throttle valve pivotally mounted within each one of said mixture conduits for movement between an open and a closed position, means forming a different idle system for supplying a mixture of air and fuel for idling to each one of said mixture conduits, said means including a different port through the wall of each mixture conduit adjacent to said throttle therein when in closed position and a different idle mixture passage extending from said fuel source to each of said ports, each of said idle mixture passages having a restricted opening into ambient space upstream of said throttles, a single by-pass passage in said carburetor body extending at one end thereof from said ambient space upstream of said throttles to another end thereof opening into ambient space downstream of said throttles for by-passing air around said throttles, an adjustable restriction in said bypass passage for controlling the flow of air therethrough, and a different air bleed passage extending from each one of said idle mixture passages downstream of said restricted opening thereof to said by-pass passage upstream of said adjustable restriction.

6. A carburetor for an internal combustion engine, said carburetor comprising a body having a source of fuel therein and a fuel and air mixture conduit therethrough, a throttle valve mounted within said mixture conduit for movement between an open and a closed position, an idle system for supplying a mixture of air and fuel for idling to said mixture conduit, said system ineluding an idle mixture outlet port through the wall of said mixture conduit at said throttle when in closed position and an idle mixture passage extending from said fuel source to said port for flow of idle fuel mixture therethrough, a bypass passage in said carburetor body opening at one end to the ambient space on one side of said throttle and at another end to the ambient space on the outer side of said throttle for by-passing air around said throttle, and means for controlling the flow of air to said idle system through said air bleed passage inversely to the flow of air through said by-pass passage, said last means including an air bleed passage interconnecting portions respectively of said idle mixture passage and said by-pass passage to provide a flow of air from said bypass passage into said idle system, and an adjustable restriction within said by-pass passage downstream of said connected by-pass passage portion.

7. A carburetor for an internal combustion engine, said carburetor comprising a body having a source of fuel therein and a fuel and air mixture conduit therethrough, a throttle valve mounted within said mixture conduit for movement between an open and a closed position, an idle system for supplying a mixture of air and fuel for idling to said mixture conduit, said system including an idle mixture outlet port through the wall of said mixture conduit at said throttle when in closed position and an idle mixture passage extending from said fuel source to said port for fiow of idle fuel mixture therethrough, a by-pass passage in said carburetor body opening at one end to the ambient space on one side of said throttle and at another end to the ambient space on the other side of said throttle for by-passing air around said throttle, and means for controlling the flow of air to said idle system through said air bleed passage inversely to the flow of air through said by-pass passage, said last means including an air bleed passage interconnecting portions respectively of said idle mixture passage and said by-pass passage to provide a flow of air from said by-pass passage into said idle system, an adjustable restriction within said by-pass passage downstream of said connected by-pass passage portion, and a restriction within said idle mixture passage downstream of said connected portion thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,621,911 Linsteadt Dec. 16, 1952 2,771,282 Olson et al Nov. 20, 1956 2,827,269 Kittler Mar. 18, 1958 as 2...? I 

